-m, --mode mode Go into the given standby state. Valid values for mode are: standby ACPI state S1. This state offers minimal, though real, power savings, while providing a very low-latency transition back to a working system. This is the default mode. freeze The processes are frozen, all the devices are suspended and all the processors idled. This state is a general state that does not need any platform-specific support, but it saves less power than Suspend-to-RAM, because the system is still in a running state. (Available since Linux 3.9.) mem ACPI state S3 (Suspend-to-RAM). This state offers significant power savings as everything in the system is put into a low-power state, except for memory, which is placed in self- refresh mode to retain its contents. disk ACPI state S4 (Suspend-to-disk). This state offers the greatest power savings, and can be used even in the absence of low-level platform support for power management. This state operates similarly to Suspend-to-RAM, but includes a final step of writing memory contents to disk. off ACPI state S5 (Poweroff). This is done by calling '/sbin/shutdown'. Not officially sup‐ ported by ACPI, but it usually works. no Don't suspend, only set the RTC wakeup time. on Don't suspend, but read the RTC device until an alarm time appears. This mode is useful for debugging.
sudo crontab -e
30 23 * * * sudo rtcwake -l -s 3600 -m mem